Skip to main content

explosive atmospheres - risk assessment of unit operations and equipment


The aim of this project is to develop a European standard which will enable manufacturers to simply and quickly assess the process parameters, identify the hazardous situations and evaluate the risks of both equipment and protective systems associated with their products and their intended use in potentially explosive atmospheres.
A risk assessment methodology for equipment and unit operations intended for use in potentially explosive atmospheres has been successfully developed. The underlying philosophy for conducting risk assessments was identified from a detailed review of existing methods. This can be summarised as an estimation of the explosion risks and its reduction to acceptable levels.

Four basic steps were identified: hazard identification, risk assessment, risk evaluation and risk reduction.

A critical and often overlooked aspect of risk assessment was the accurate definition of the function of the machine / system to be assessed. The methodology therefore includes a novel procedure for the preparation of an "Equipment/Process Flow Diagram" to ensure that the intended use of the equipment is correctly defined. Forms for recording the results of the methodology have been included to ensure that the results can be audited.

The needs of users of the methodology has been taken into account by using the responses of a questionnaire received from over 200 manufacturers and users of such equipment, a review of incidents involving such equipment as well as the results of trials of the draft methodology with manufacturers. The final version includes logic diagrams to guide the user and a "User-Guide", which contains detailed examples of the use of the methodology for assessing the risk associated with different types of equipment and unit operations. These examples have been based on the trials carried out and include risk assessment of a pneumatic powder unloading system, a spray drier for milk powder, part of an oil seed extraction plant, paint spay booth and an explosion door. Throughout the RASE project the work was widely publicised with presentations being made at many National, European and International meetings. The methodology can be freely downloaded from the Internet at The methodology has been written in a form that can be readily adopted as a European standard in support of the ATEX and Machinery Directives and this is being carried out by CEN/TC305/WG4.
EU Directives 89/392/EC and 94/9/EC contain Essential Safety Requirements relating to safety which are to be applied by manufacturers of equipment and protective systems intended for use in potentially explosive atmospheres. Current standardisation work only considers the basic concepts and methodology dealing with explosion prevention and protection. Manufacturers need to carry out a risk assessment of their equipment to identify the hazards, which may arise during its use, and to enable them to specify appropriate safety measures. There is a lack of methodology when facing the design of various equipment and protective systems intended for use in explosive atmospheres.

Work programme
The project has been divided into four discrete tasks:
TASK 1: Inquiry on Current Experience from Manufacturers
TASK 2: Development of Risk Assessment Methodology
TASK 3: Application of the Methodology for Various Types of Equipment
TASK 4: Comparison of the Results and Development of the Final Methodology.

Funding Scheme

CSC - Cost-sharing contracts


August-thyssen-strasse 1
59067 Hamm

Participants (5)

38,Fantoftveien 38
5892 Bergen
Forschungsgesellschaft für AngewandteSystemsicherheit und Arbeitsmedizin eV
Dynamostraße 7-9
68165 Mannheim
Health and Safety Executive (HSE)
United Kingdom
Broad Lane
S3 7HQ Sheffield
Institut National de l'Environnement Industriel et des Risques
Parc Technologique Alata
60550 Verneuil-en-halatte
Niro A/S
2860 Soeborg